Cut-back asphalts are in current use as mastic coatings for highway construction and built-up-roofing (BUR) applications. Such cut-back asphalts are usually prepared by adding mineral spirits (naphtha) to an asphaltic base.
Used as a mastic coating for insulating and weather-proofing roof membranes, these cut-back asphalts have several advantages, one of which is the ease of application. They are usually mopped or sprayed in a cold (ambient) state over roof membranes, and then allowed to dry. An additional layer of granules or gravel can be applied over the mastic-coated membrane to provide protection from heat and ultraviolet radiation, as taught in U.S. Pat. No. 4,521,478; issued: June 4, 1985 to John P. Hageman.
While cut-back asphalts have gained commercial acceptance in roofing applications and construction, they have not achieved their complete potential due to several drawbacks and disadvantages, such as:
1. Cut-back asphalts remain tacky from 3 to 4 weeks after application, causing considerable delays in completion of the construction project. Roofs cannot be walked upon and inspected until the asphalt is dry.
2. Cut-back asphalts present a dangerous fire hazard because of their highly flammable nature. Cut-back asphalts have a low flash point of approximately 50 degrees F. (open cup).
In order to decrease the flammability of the asphalt, flame retardant fillers such as asbestos have been utilized. However, asbestos has been coming into increasing disrepute as a carcinogen, and its use in the building trades is on the wane. In addition, asbestos does nothing to improve the drying characteristics of the asphalt, and is also a fairly expensive component.
The invention seeks to provide an asphalt additive which retards flammability, and is inexpensive.
The invention also has as one of its objectives to provide an additive which will decrease the drying time of the mastic coat.